Treatment of lubricating oils



Jam. i6, E951 MT E. NASH TREATMENT oF LUBRTCATING ons Filed Sept. 8, 1947 HJNN OLLOVEI .-i

Patented Jan. 16, 1951 aTREATMENT-OF LUBRICATING OILS Martin Nash, Bartlesville, Okla., Aassignor -to Bhillips lItetrcleimrn Company, :a .1 corporation of Applicationseptember.8, 1947, Serial No. 772,877

`-I'IClaims- (Cl. 196:1419) '.This invention' relates ltolthe treatment ofjuv- Lbricating oils :to improve their properties. 'In .one of itsmorespecicaspects it relates toa treatment of a.' lubricatingoil Whichjincrea'ses its 'viscosity or -viscositylindexy and Avotherwiseirnl.proves various` proper-ties.

v`iLubricating .o'il' as referred'to herein includes all such products,.raridtheirbase stocks, which Lhaveiaviseo'sity .of abot.I32 ,S.US ISaybo'ltllniaversal `Seconds) at. 210.,F, .to about 350SUSA-a`t 210LJEL, and. as areeusually understood tobecov- .ered-,by:fthisermbythosa skilled intheiart. llt includes '.par'ticularly lubricating oil..stocks, such ,as sa; parail'inebase. stock,..a. naplithene-base (stock, a ,mixed-...basesstoeh ...orma synthetic-lfbase stock, which .are @refined tor usesas engine lubricants. LBy. blending-.these neutrals. and b'right stocks '.engine lubricating .oils of varying viscosity [ind "dices arepro'duce'd.

Lubricating .oils )of Nhigh quality have been mamifactur'e'd` by'imany:processesincluding sul- L'furie 'acid' refining, `Aaluminum .chloride refining,

solvent rening, "andi" hydrouoric acid rening. AThe`siiliu1rvic-- acid `processimprovessome uof *the fjproperties" of *theoil lbut `in `-doing 'sof a `largepor- "tion-of t-he acid; is 'consumed ing the Vprocess and *is fnot lfecononiically lrecoverable. 'T-he Isulfuric @acidi-sidlfurdioxide fproccss has the samedisad- 'fvaiitaga in thatl a n'greater lp'art f A'fthe acid Y#is v-nonr'ecoverable, making the process #overly dex- "pens-ive. `-Solventlfirein'ing :processes L are known in'fthe.V prior .artFusingsulturfdioxide. Iv Theylfalso 'improve some. :of fthe .properties :of the' lubricatvingroilsbutifalso'leave:'iobjectionablef:sulfur,ucomlpoi-mds. I-Iydrufluoriccacid:'rening as'. showniin fthe prior fart improves lfso'me irprope'rties iof-'lu- .':bricating voili by 'i removing 'igumf-formifngffcom- 'pounds, fcleiins, and eat"- relatively ,fzlovv Apressure small amounts of aromaticsfand;.maygpnomote 40 .alkylationbetween some -of4 thecompoundsavvhich are-usually, present.

nlroadly.speaking,` my invention :compri-sesgo. @process .of. improvingllibricatiifiga.oil 1by.:contac.t

.ing fthe -lubricating oil h@with esubstantiallyan- 45 unsaturated resins, Vgum#forming bodies, and other undesirable-components are removed by thehydroluoricacidesulfur dioxide mixture. An added advantage of l the hydrofluoric acid-sulfur f'clioxi'de ftrea'tmentis the recovery by solvent extractionof i' the sulfur fdioxide which is usually Llost Whenuse'dralone or in-other combinations, and by inhibiting 'fthe Lkformationof undesirable sulfur compounds. fIf-fdesired, alight hydrocarfbon-maybeusedlasi-a"diluent forthe oil during =treatment, `such diluent generally being a `readily fliquei-"iable parafIr-suchaasffliquid-propane, etc.

VInf-1a preferred embodiment of this invention, V"the l'treatedcoil VisUsubsequentl-y contacted with vsubstantially anhydrous -hydrofluoric acid'to remove any 'residual' undesired sulfur compounds.

Anobject-ofthepresentinvention is to provide anove1and improved method of improvfing lubricatingb'ils. v./.kno'ther Objectis to :provide :a *method of "improving ynatural lubricating "oils, -A'pfurther object' is-toprovide-a-method of improving mixed-base lubricating oils. VAnother 'object Vuis to fprovide amethod of improving the viscosity index 10i-"natural Ior synthetic lubricatingwoils Other objects and Vadvantages of this 'invention vvillmbecome"apparent from the accompanying ldisclosure vand discussion vrThe "accompanying Mdrawings illustrate diagrammatica'llyztwo embodiments of apparatus forithe Apractice `off theupresent invention.

.A mostimportant'improvement in the yoils Jtreated by' thejpresentprocess is inthe viscosity index;which is determinedgby the method described 'in an article entitledViscosity Variations .of Oils With Temperatures,"by W. Dean .and

" G." Davis, .in'Chemical and Metallurgical -Engineerinf-r,`Y volume' 36, f page "619 (1929) The viscosity-indexOf a" lubricating oil' is .an indica- .tionof-its Ycomposition .or type, i. e., Whether tlit :is a jparan-base or nallhtheneebase oil. "Paraflin-base oils"1have'high .viscosity indices, *naphthenebase oils' have krelatively low viscosity indices, andmixe'd-.base oils have viscosity indices ^between`ftheseextremes "This index is likewise aimeasure ofthe ability of a lubricating oily to rehmain viscous at Vhigh `temperatures. As is well "known,ils'lose-their viscosity rapidly with. an Iincreaseintemperature The oil with a'high "viscosity index-wilL-however, lose its viscosity less rapidly'than' an oil-withfa'low viscosity index when the temperature isgincreased, or conversely, Will-notfhave Vits viscosity' unduly increased by a; lowering ofI temperature. The present inven 'tion increases this viscosity index and may also lincrease the absolute viscosity at'the standard "'210'F.itemperaturefor measurement of vis- ...cosity Any suitable equipmentl may be employed for the performance of the present invention, and equipment which is resistant to the corrosive action of hydrofluoric acid is particularly desirable. Conventional contacting equipment similar to contactors which are commonly used for conducting the alkylation of isoparains with olens may be used to provide suitable contact between the reactants. Any other means of maintaining an intimate contact of the lubricating oil and acid phases may be employed. The equipment should be provided with means for maintaining the desired temperatures and pressures in the various zones.

The temperature range necessary for the practice of this invention is from about 20 to about 50 F. The pressure is not critical, but sufficient pressure is preferably used to maintain all reactants in liquid phase. The reactants should be contacted for a sucient length of time for the improvement of the oil to take place. The treating time for the oil, hydrouoric acid, and sulfur dioxide mixture is about 30 to about 300 minutes, and for the oil and hydroluoric acid mixture is about 5 to about 30 minutes.

In the performance of one embodiment of the present invention, a lubricating oil may be treated according to the process described above, allowed to separate, usually by gravity, into two separate layers, namely the lower layer or acid phase and the upper layer or hydrocarbon phase. A portion of the lower layer or acid phase is recycled to the initial contactor and the remainder is passed to a fractionator where the hydroiiuoric acid and sulfur dioxide are recovered. The upper layer or hydrocarbon phase is passed to an extractor where it is treated with hydroluoric acid.

In the performance of the second embodiment of the present invention, a lubricating oil may be treated, according to the process described, in an initial contact zone with a mixture of substantially anhydrous hydroluoric acid and sulfur dioxide and in a second contact zone with hydroiiuoric acid alone. The treated oil is then fractionated and the hydroiiuoric acid-sulfur dioxide mixture removed for further fractionation;

In either of the above embodiments of this invention, if desired, the hydrouoric acid and sulfur dioxide may be introduced to the contactor separately, however, the preferred method is to mix the acid and sulfur dioxide prior to introducbatchwise manner or continuously, the latter being preferred for commercial operation. A better understanding of this invention may be had by reference to the accompanying drawings which illustrate, by means of a diagrammatic flow sheet, an over-all process of a preferred embodiment of the present invention.

As shown in Figure 1 lubricating oil is introduced through line I0 to a contactor II, the hydrofluoric acid and sulfur dioxide mixture in the weight ratio of sulfur dioxide to hydrofluoric acid of about 1:3 to about 3:1 is introduced to contactor I I through line I2, and a low boiling parafnic diluent such as isopentane is introduced through line I3, valve I4, and line ID. The range of ratios of oil to hydroiiuoric acid-sulfur dioxide is from 1:5 to 5: 1, depending on the properties of the material to be treated. The four components are intimately mixed in contactor Il for a suitable reaction period and the effluent passed through line I5 and valve I6 to settler I'I in which separate an upper or hydrocarbonrich layer and a lower layer rich in hydrofluoric acid and sulfur dioxide. At least a portion 0f the lower layer may be recycled through line I9 and valve 20 to contactor II; the remainder is passed through line 2I and valve 22 to fractionator 38. In fractionator 38 the acid-sulfur dioxide mixture is fractionated to yield a highboiling organic material which is removedthrough line 39 and valve 40; a hydrofluoric acidwater azeotrope, removed through line 4I and. valve 42; and a hydrofluoric acid-sulfur dioxide? fraction, removed through line 43 and valve 44' to fractionator 45. The hydrouoric acid and sulfur dioxide are separated in fractionator 45, the sulfur dioxide removed overhead through line I2 and valve 47, and anhydrous hydrciiuoric acid removed as a bottoms product through line 49 and valve 50. Aportion of the hydrofluoric acid stream carried through line 49 is passed to line I2 through line 5I and valve 52, and a mixture of hydrofluoric acid and sulfur dioxide thus recycled to contactor II via line I2, thence following a previously described route. The remaining hydrouoric acid carried in line 49 is introduced to extractor 23 through valve 24, following a route subsequently described. Make-up hydrofluoric acid may be added to line 49 through line 53 and valve 54, and make-up sulfur dioxide may be added through line 55 and valve 56 to line I2.

The upper layer obtained in settler II is passed through line 25 and valve 26 to extractor 23 in which it is countercurrently contacted with hydrofluoric acid which enters through line 49.- Hydrofluoric acid Withdrawn from extractor 23 is passed through line 2'I, valve 28, and line I9 to contactor Il. In extractor 23 undesired sulfur compounds remaining in the oil are extracted by the hydrouoric acid. In some casesgespecially when contactor II is maintained substantially above 20 C. it is advantageous to maintain extractor 23 at a lower temperature, e.' g., about 20 to about 0 C., in order to improve the color of the oil. Furthermore, in some cases the hydroluoric acid entering through line 49 may constitute all the acid charged to the contactor and the material charged through line I2 may be substantially pure sulfur dioxide. In this mode of operation, valve 52 is closed.

Extracted hydrocarbon eiiiuent from extractor 23 is passed through line 29 and valve 30 to fractionator 3|, which may be operated at subatmospheric pressure if desired. An overhead fraction comprising chiefly low-boiling paraffin and hydrofiuoric acid is withdrawn from fractionator 3I through lines 32 and valve 33 and recycled to contactor I I. A kettle product having a boiling range similar to the untreated oil is withdrawn through line 34 and valve 35 as the main product of this process. This oil may be further treated by such conventional methods as alkali washing, clay treating, etc., as desired.

The contactor described in Figure 2 as a second embodiment of this invention takes the place of contactor I I, settler I1, and extractor 23. Where the same identification numerals are used in both lzflowerzona Afffxture hydroluorictacidfand i eenterslcontactol throughintermediat "nletfiiZ,

The "da^ta""'from"Y Example 'i I""show that a `rsubstaiitialincrease invis'cosity in'dexis obtain'ed'fby *treajtrxentwi'th hydru'oric acidiand suliur di- Example I y '40 "oxide IV"iiue' '-high'neutralizationnumber"before A mixture of 880, grams of lubricating 011,.-627 ""hotini) SduotO'"the"presence" of unv"grams bf-anhydrous nidrolucricfaciditia'grams ifstzameasmfur*"compounds,- andm2y""be "lowerfd of isopentane, and 418 gramsof""s'i1lfur"dioxide "bya*subsequenttreatrneiit'with hydrofluoric vacid was shaken-,inea-Monell.bombaforftwo hours at Valone. "iTheSTll/Icolormay also be'l'oweriedi in room temperatures by means. of a rocker mecha- 4) lTSfmaTiIlIt nism. '-"'he bomb was removed from the'ock'er "ComparisonofthefdatafromExampl Il'with "and ali'owedito ystand'in'afverticalpositionforbice that of Example I indicates the beneficialeiects hour,aiter-"which"thehydronoric acid lur fof treatment withinixtures'ofhydrouoric 'acid ld'io'xide layer-wastremov'ed. The"treat`e"d`"dil-"isoim. ardrsvil'furdi'oxide. "WhensulfurL'dioxide was pentane mixture was then washed'with dilute "present thenncre'aseinviscosityindexwasabout sodium hydroxide and filtered through Hyo 5 per cent, whereas, when sulfur dioxide was ab- Super-Cel. The filtered oil was topped under sent the increase was only about 0.3 per cent. vacuum to the initial boiling range of the Although the process has been described and original oil. The properties of the product oil 55 exemplified in terms of its preferred modica- Were determined by conventional methods. The tions, it is understood that various changes may following results were obtained. be made without departing from the spirit of the process as disclosed and expressed in the claims.

untreated Treated I claim: Y

l A 1 6U 1. A process of manufacturing a lubricating oil of improved properties which comprises thor- 34M 333.9 oughly agitating a lubricating oil with a mixture 53.39 53.36 of anhydrous hydrouoric acid and sulfur diox- Pour pointln 851g 901g ide, containing about 25 to '75 weight per c-ent M @Olgr 282g 29 65 sulfur dioxide, in the ratio of oil to treating mixaVl Refrrtive'ndex am? o 1,4893 1 4866 ture of about 1:5 to about 5:1, at suuiclent pres- Alummum @109k Stablhty data: sure to maintain the hydrofluoric acid and sulfur Neutralization No.- l

forehhetmg g dloxlde substantlally liquid, and at a temperature ter ea ing o o Ramsbottomoresnwhper @M between about 20 and about 50 C., and foi Before heating.- 0.04 0.18 70 about 30 to about 300 minutes.

0'17 040 2. A process of manufacturing a lubricating Epercent 1 E t 020g oo oil of improved properties which comprises thorvaporation oss, W per een Viscosity increase corr. for evapn. loss, Oughly agltfrltlng al lllbllatlng O11 Wltll a Il'llXtllIe per cent 6-7 of substantially anhydrous hydrouorlc acid and 75 sulfur dioxide, containing about 25 to 75 Weight per cent sulfur dioxide, in the ratio of oil to treating mixture of about 1:5 to about 5:1, and further extracting said oil with substantially anhydrous hydrofluoric acid in the ratio of oil to hydrofluoric acid of about 1:5 to about 5:1, at suiicient pressure to maintain the hydrofluoric acid and sulfur dioxide substantially liquid, and at a temperature between about .-20" and about 50 C., and for about 30 to about 300 minutes.

3. A process of manufacturing a lubricating oil of improved viscosity index which comprises treating a lubricating oil in an initial contact zone with substantially anhydrous hydrofluoric acid and sulfur dioxide, separating the treated mixture into an acid phase and a hydrocarbon phase, separating said acid phase into a heavy hydrocarbon fraction, a hydrofluoric acid-Water azeotrope fraction, and a hydrouoric acidsulfur dioxide fraction, separating said acidsulfur dioxide fraction into hydrouoric acid and .sulfur dioxide for recycle, recycling at least a portion of said separated hydrofluoric acid and sulfur dioxide to said initial contact zone, and fractionating said hydrocarbon phase recovering said improved lubricating oil.

4. A process of manufacturing a lubricating oil of improved viscosity index which comprises treating a lubricating oil in an initial contact zone with substantially anhydrous hydroiiuoric acid and sulfur dioxide, separating the treated mixture into an acid phase and a hydrocarbon phase, separating said acid phase into a heavy hydrocarbon fraction, a hydrouoric acid-water azeotrope fraction, and a hydrouoric acid-sulfur dioxide fraction, separating said acid-sulfur dioxide fraction into hydrofluoric acid and sulfur dioxide for recycle, recycling said separated sulfur dioxide to said initial contact zone and at least a portion of said separated hydrofluoric acid to a subsequently described hydrocarbon extraction zone, contacting countercurrently said hydrocarbon phase with hydrofluoric acid in an extraction zone, recycling said acid after contact with said hydrocarbon phase to said initial contact zone, fractionating the resulting extracted hydrocarbon and recovering said improved lubricating oil.

5. A process of manufacturing a lubricating oil of improved viscosity index which comprises treating a lubricating oil in an initial contact zone with substantially anhydrous hydrofluoric yacid and sulfur dioxide, and further treating said oil in a second contact zone with substantially anhydrous hydrofluoric acid, separating the treated mixture into an acid phase and a hydrocarbon phase, separating the hydrouoric acid from said acid phase, recycling at least a portion of said separated hydrouoric acid, fractionating said hydrocarbon phase, and recovering said improved lubricating oil.

6. A process of manufacturing a lubricating oil of improved viscosity index which comprises thoroughly agitating a lubricating oil with a mixture of substantially anhydrous hydrofluoric acid and sulfur dioxide, in the volume ratio of oil to treating mixture of about 1:1, for about 30 to about 300 minutes, at suicient pressure to maintain the hydroiluoric acid and sulfur dioxide substantially liquid, at a temperature between about 20 and about 30 C., and recoveringl the said improved lubricating oil as a product of the process.

7. A process of manufacturing a lubricating oil of improved viscosity index which comprises thoroughly agitating a lubricating oil with a mixture of substantially anhydrous hydrofluoric acid and sulfur dioxide, in the volume ratio of oil to treating mixture of about 1:1, for about 30 to about 300 minutes, at sumcient pressure to maintain the hydrouoric acid and sulfur dioxide substantially liquid, and at a temperature between about 20 and about 30 C.; further extracting with liquid substantially anhydrous hydrofluoric acid in the volume ratio of oil to hydrofluoric acid of about 1:1, for about 5 to about 30 minutes, at a temperature between about 20 and about 30 C., and recovering the said improved lubricating oil as a product of the process.

MARTIN E. NASH.

REFERENCES CITED The following references are of record in the le of this patent:

y UNITED STATES PATENTS Number Name Date 2,378,762 Frey June 19, 1945 2,438,565 Linn et a1. Mar. 30, 1948 2,440,258 Elliott et a1. Apr. 27, 1948 

1. A PROCESS OF MANUFACTURING A LUBRICATING OIL OF IMPROVED PROPERTIES WHICH COMPRISES THOROUGHLY AGITATING A LUBRICATING OIL WITH A MIXTURE OF ANHYDROUS HYDROFLUORIC ACID AND SULFUR DIOXIDE, CONTAINING ABOUT 25 TO 75 WEIGHT PER CENT SULFUR DIOXIDE, IN THE RATIO OF OIL TO TREATING MIXTURE OF ABOUT 1:5 TO ABOUT 5:1, AT SUFFICIENT PRESSURE TO MAINTAIN THE HYDROFLUORIC ACID AND SULFUR DIOXIDE SUBSTANTIALLY LIQUID, AND AT A TEMPERATURE BETWEEN ABOUT -20% AND ABOUT 50* C. AND FOR ABOUT 30 TO ABOUT 300 MINUTES. 